Despite considerable effort and characterization, the precise role of PKA in regulating sperm development arid the acquisition of motility and fertilization competence remains unclear. A major roadblock in these studies has been the lack of techniques to manipulate the expression and activity of PKA in sperm cells since no readily accessible cell culture model is available that allows genetic intervention. This proposal continues our efforts to apply mouse genetic approaches to modify the subunits of PKA and address questions that relate to the importance of subcellular localization, PKA activation state, and developmental changes in subunit isoforms. The specific aims of our proposal include: (1) Analyze the role of S-AKAP84/D-AKAP1 in the development and survival of spermatids (2) Determine the role of C subunit during spermatogenesis (3) Examine the anchoring of Rl and its physiological significance during spermatogenesis (4) Identify specific PKA substrates in sperm and develop a mechanism to inhibit sperm PKA In vivo. These studies are relevant to larger questions concerning the treatment of infertility and the development of male-specific contraceptive approaches.